Method and apparatus for treatment of monofrequency tinnitus utilizing sound wave cancellation techniques

ABSTRACT

Tinnitus is defined as sound(s) heard by an individual when no external sound is present and often takes the form of a hissing, ringing, chirping or clicking sound which may be either intermittent or constant. According to the American Tinnitus Association, tinnitus affects tens of millions of Americans and many suffer so severely from tinnitus they are not able to function normally on a daily basis. Unfortunately the exact cause or causes of tinnitus are not understood by the medical community and thus many tinnitus sufferers are told by their doctors to “learn to live with it”.  
     In accordance with novel aspects of Applicant&#39;s monofrequency tinnitus patient treatment apparatus and process, phase cancellation effects are achieved by utilizing an externally generated sound which is subjectively selected by the monofrequency tinnitus patient to match in both tone and loudness his or her tinnitus sound. This subjectively selected externally generated sound wave which matches in tone and loudness the patient&#39;s tinnitus sound, is either (i) sequentially phase shifted through a plurality of phase shift sequence steps totaling at least 180 degrees or (ii) alternatively is directly phase shifted in essentially a single step motion into a 180 degree, out-of-phase reciprocal, canceling relationship with the patient determined tinnitus tone. The sequential steps of the phase shifted tone or the directly phase shifted tone are applied to the tinnitus patient to effect cancellation or diminishment of the patient&#39;s tinnitus.

CROSS REFERENCE TO RELATED U.S. APPLICATION

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/272,461 filed Mar. 2, 2001, the specification anddisclosure of this related application is incorporated herein in itsentirety by this reference.

TECHNICAL FIELD

[0002] Applicant's inventions are related to the treatment of tinnituspatients and more particularly to improved methods and apparatus fortreatment of monofrequency tinnitus patients utilizing phase shiftcancellation principles.

BACKGROUND OF THE INVENTION

[0003] Tinnitus is defined as the perception of sound by an individualwhen no external sound is present, and often takes the form of ahissing, ringing, roaring, chirping or clicking sound which may beintermittent or constant. According to the American TinnitusAssociation, tinnitus afflicts more than 50 million Americans and morethan 12 million of those suffer so severely from tinnitus that they seekmedical attention and many cannot function normally on a day-to-daybasis.

[0004] Tinnitus, often referred to as ringing in the ears, is estimatedto be present in approximately 50% of the US population over 65 years ofage. In general,. tinnitus takes many and varied forms which may berelated to its underlying cause. Tinnitus may be caused by or related tosuch diverse factors as trauma, drugs, hearing loss, the normal agingprocess or other unknown causes.

[0005] In 1825 Dr. Jean-Marie Gaspar Itard published a book in Francetitled Maladies of the Ear in which he stated that tinnitus is a medicalproblem and that most patients suffering with severe tinnitus did notrespond to medical treatments available at that time and most in themedical community believe that is still true today despite majoradvances in the medical sciences. Itard suggested that external soundsbe utilized to interfere with (masking) the tinnitus sound heard by apatient and could be relieved in some instances provided the maskingsound bore some relationship to the tinnitus sound heard by the patient.

[0006] As early as 1930 Dr. R. I. Wegel published a paper entitled “AStudy of Tinnitus” in which he reported his findings that tinnitus is apathologic system but that quantitative studies had not been carriedforward to a point of being useful in patient diagnosis or effectivetreatment. The idea of using an external sound generator to mask anobtrusive tinnitus condition dates from 1928 to a work by Drs. Jones andKnudsa although many credit Saltzman and Eisner (1947) with the firstsuccessful masking treatment for tinnitus.

[0007] During the 1960s and 1970s additional tinnitus research wasconducted at a number of US medical facilities including the OregonHearing Research Center in Portland. The Oregon Center began as alaboratory project to study tinnitus induced in animals by drugs.According to Jack Vernor initially through incidental tinnitus patientcontacts, the Oregon Center gradually shifted from an animal lab focusto tinnitus patient clinic to study tinnitus and eventually develop atinnitus masking device. The Oregon Tinnitus Masker Study resulted in anumber of patient specific device recommendations including hearingaids, tinnitus maskers (sound generators) and tinnitus instruments whichcombine both a hearing aid with a sound generator. Early reports of theOregon Masker Project reported substantial success in masking treatmentsfor tinnitus patients utilizing all three devices and initially claimeda success rate in the range of 67% for tinnitus patients who acceptedthe Oregon recommendation of a hearing aid and 81% of tinnitus patientswho accepted the recommendation for a tinnitus masker/instrument. Areport by Dr. McFadden for the Working Group 89,NRC criticizes theseearly success reports and states that perhaps they were misleadinglyoptimistic.

[0008] In reporting on patient studies at the Oregon Tinnitus Clinic,Jack Vernon, director of Oregon Hearing Research Center, stated that inpatient tinnitus studies phase and tone relationships are of obvious andcritical importance in tone masking of tinnitus. Vernon goes on to statethat one cannot repress the idea of canceling tinnitus by a proper phaseadjustment of the external tone used in masking. In commenting onWegel's earlier tinnitus treatment findings that a slight mistuning of amasking external tone produced a beat-like sensation with the tinnitussound, Vernon reported that in a 100 patient study he was able to detecta slight beat-like sensation in only four instances. Vernon thereforeconcluded that the beat-like sensation found by Wegel was most probablydue to octave confusion resulting in Wegel not using a single pure tonebut rather a narrow band of noise. In conclusion, Vernon observed thatphase manipulation justifies further patient studies as a maskingparameter for tonal tinnitus treatments. Vernon's report on possiblephase manipulation for treating tinnitus patients remained unchangedfrom its original publication in 1991 and as included in the 1997edition of Shulman's treatise entitled “Tinnitus Diagnosis andTreatment.”

[0009] In “The Origin of Tinnitus,” J. Tonndorf states that littlefactual information exists about the mode(s) of tinnitus generation.Even today medical approaches to identifying and treating tinnituscontinue to be hampered by what little is known about the human auditorysystem. According to A. Shulman in his 1997 treatise“Tinnitus/Diagnosis/Treatment”, attempts to understand and treat orcontrol tinnitus are unfortunately still limited by the lack of suitablemodels and therefore more flexibility in thinking about and treatingtinnitus will be required in order to foster the development of newmedical modalities in the diagnosis, treatment and control of tinnitus.Unfortunately today many patients suffering from tinnitus are too oftentold by their doctors that no effective cure or treatment exists andtherefore they will just have to learn to live with their affliction.

[0010] To remedy the current deficiencies in diagnosing and treatingtinnitus patients and more particularly monofrequency (single tone)tinnitus, Applicant has developed a new, more efficient phasecancellation treatment process and apparatus that overcomes many of theshortcomings taught by the prior art.

[0011] There is a long-felt need for an effective treatment formonofrequency tinnitus patients to substantially reduce, relieve oreliminate the often substantially debilitating condition of tonaltinnitus.

[0012] Glossary

[0013] Amplitude—The instantaneous amplitude of an oscillating quantity(e.g. sound pressure) is its value at any instant, while the peakamplitude is the maximum value that the quantity attains. Sometimes theword peak is omitted when the meaning is clear from the context.

[0014] B ats—Periodic fluctuations that are heard when sounds ofslightly different frequencies are superimposed.

[0015] Clinical types of Tinnitus—Refers to a specific entity that canbe identified by clinical and laboratory means.

[0016] Combination tone—A tone perceived as a component of a complexstimulus that is not present in the sensations produced by theconstituent components of the complex when they are presented alone.

[0017] Cycle—That portion of a periodic function that occurs in oneperiod.

[0018] Dichotic—The sounds reaching the two ears are not the same.

[0019] Diotic—The sounds reaching the two ears are the same.

[0020] Frequency—For a sine wave, the frequency is the number of periodsoccurring in one s. The unit is cycles per second, or Hz. For a complexperiodic sound, the term repetition rate is used to describe the numberof periods per second (pps).

[0021] Harmonic—A harmonic is a component of a complex tone whosefrequency is an integral multiple of the fundamental frequency of thecomplex.

[0022] Loudness—Subjective impression of the intensity of a sound, orthe intensive attribute of an auditory sensation, in terms of whichsounds may be ordered on a scale extending from quiet to loud.

[0023] Masking—The amount (or the process) by which the threshold ofaudibility for one sound is raised by the presence of another (masking)sound.

[0024] Octave—The interval between two tones when their frequencies arein the ratio 2:1.

[0025] Phas—The phase of a periodic waveform is the fractional part of aperiod through which the waveform has advanced, measured from somearbitrary point in time.

[0026] Pur tone—A sound wave whose instantaneous pressure variation as afunction of time is a sinusoidal function. Also called a simple tone.

[0027] Sin wave, sinusoidal vibration—A waveform whose pressurevariation as a function of time is a sine function. This is the functionrelating the sine of an angle to the size of the angle.

[0028] Ton—A sound wave capable of exciting an auditory sensation havingpitch.

[0029] Wav form—The form or shape of a wave. It may be representedgraphically by plotting instantaneous amplitude, pressure, or intensityas a function of time.

[0030] White noise—Broadband noise having constant energy per unit offrequency.

SUMMARY OF APPLICANT'S INVENTION

[0031] Tinnitus is often understood by a layman as a sound heard by anindividual when there is no external sound present. According to theAmerican Tinnitus Association, more than 50 million Americans sufferfrom tinnitus and unfortunately the cause or causes of tinnitus are notwell understood by the medical community and there is currently no curefor the affliction so many tinnitus sufferers are often told by theirdoctor to learn to live with it.

[0032] In accordance with novel aspects of Applicant's novel apparatusand method, a monofrequency tinnitus patient is first sound-typedsubjectively by the patient in terms of the frequency and amplitude(loudness) by comparing the tinnitus sound to the output of an externalsound generator. The tinnitus patient adjusts the output of the soundgenerator until an exact match is identified and preferably thissubjective sound typing is repeated a number of times in a blind manner,i.e. the patient during the sound-typing process does not see thefrequency and amplitude displays of the sound generator. Based upon thesound-typing data, an external sound generator generates a sinusoidaltone equal in frequency and amplitude to the patient's monofrequencytinnitus sound and this externally generated tone is then phase shiftedin a step-wise fashion or alternatively in a direct single motionthrough at least 180 degrees whereby the generated tone is phase shiftedrelative to an arbitrary point through a reciprocal relationship withthe patient's tinnitus tone and the shifted sound wave is applied to thepatient via high quality earphones thereby effecting a cancellation or asubstantial diminishment of the patient's tinnitus tone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a block diagram of monofrequency tinnitus treatmentapparatus in accordance with aspects of Applicant's invention.

[0034]FIG. 2 is a series of sine waves which graphically illustratephase shift cancellation principles in accordance with further aspectsof Applicant's invention, and

[0035]FIG. 3 is a logic flow diagram illustrating one of Applicant'spreferred sequence of steps to implement Applicant's phase shift processfor treatment of monofrequency (pure tone) tinnitus patients.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0036] Referring now to FIG. 1, the preferred embodiment of apparatusfor Applicant's novel phase shift treatment of monofrequency tinnituspatients is illustrated in block diagram form. A sound generator 10,which may be an Agilent model 33120A function generator or anyequivalent commercially available wave form generator, is coupled to apatient's headset 12 and to an input of an oscilloscope 14 which may,for example, be of the type commercially available in the U.S. fromTektronics, Inc. A second sound generator 16 is also coupled to anotherinput of oscilloscope 14.

[0037] Sound generator 10 has a plurality of adjustable knobs 18, 20 and22 and an output terminal 24. As will be hereinafter explained infurther detail particularly with respect to FIG. 3, a monofrequencytinnitus patient is asked to adjust knobs 18 and 20 of sound generator10 until the output of the sound generator applied to headphones 12matches the tinnitus monofrequency tone heard by the patient. Thissubjective “sound-typing” is preferably repeated a plurality of times ona blind basis, i.e. the patient cannot see the readout display, notshown, on the sound generator and the subjective sound typing data foreach of the self-typing steps is recorded by an attending audiologist orphysician.

[0038] The principles of sound wave cancellation by superimposing, e.g.summing, a second sine wave having the same frequency and amplitude, asthe first sine wave with a phase shift of 180 degrees is well understoodin the electrical and measurement arts and is utilized in many technicalfields including audiology, mechanics and electronics generally. Toprove the phase shift cancellation effect of summing two waves of thesame frequency and amplitude but without any knowledge of the phaserelationship of the first wave to the second wave relative to a commonpoint, can be illustrated as follows. Sound generator 10 is set to afirst tone having a frequency of f and an amplitude of A (for example inmilli volts as displayed on sound generator 10) and connected to thefirst input of multi-beam oscilloscope 14. A second generator 16 is alsoset to the same tone of f with a like amplitude and the output isconnected as a second input to oscilloscope 14.

[0039] With reference to FIG. 2 it may be seen that by adjusting thephase of sinewave f₁ through a series of steps, illustrated as f₂ . . .f_(n), the sum of f₁ plus f_(n) neutralizes or cancels and asillustrated f₁ plus f_(n) cancel when f_(n) is 180 degrees out of phasewith f₁. Unfortunately for tinnitus patients, the structure andoperation of the human auditory system is much more complex than thesimple addition of two tonal sound waves as illustrated above on amulti-trace oscilloscope 14.

[0040] It is well understood in the field of audiology that humans andanimals can determine, to a considerable degree of precision, thedirection of a sound wave remote from them and to some extent canestimate the distance of a sound source from an observer. Numerousexperiments in the field of audiology have attempted to analyze themechanics by which so-called binaural localization is accomplished inhumans and animals. There are two primary factors which assist one indetermining the direction of an arriving sound: (1) relative intensityin the hearer's two ears and (2) the difference in phase between theears or for a sinusoidal tone, the difference in phase between the soundwaves arriving at the right and left ear of the hearer respectively.Thus it is clear that a human or animal auditory system can distinguishphase shifts of complex sound signals and for pure or monofrequencytones specifically. This type of auditory analysis is frequencydependent and for frequencies above 1 K hertz most observers tend todetermine the direction of a sound source from the side of the earreceiving the louder sound. Thus in general it appears that auditorylocalization by phase difference is most definite for a band offrequencies in the order of 1 to 51 K hertz. As discussed hereinafterwith reference to FIG. 3, in implementing tinnitus treatments it isimportant to determine not only the tonal quality of the tinnitus signalbut whether the tinnitus patient hears his/her tinnitus in both ears, inonly one ear or as many patients indicate when asked where they hear thetinnitus they respond in their head without reference to either theirright or left ear.

[0041] Referring again to FIG. 1, the structure and operation ofApplicant's preferred embodiment of apparatus for treating monofrequencytinnitus patients will be further described. A phase shift network 30may be of any type known to those skilled in the auditory and electricalarts. Applicant's preferred embodiment of sound generator 10 is of thetype commercially available from Agilent as model 3312A functiongenerator, which incorporates an output waveform phase shift feature. Toselect the waveform phase shift feature, an operator may dial in thedesired phase shift (scaled in degrees) by turning knob 22 to theappropriate phase shift factor, e.g. 10 degrees, 20 degrees etc. whichaffects the desired shifts, e.g. of delta 1, delta 2, etc. as shown inFIG. 2.

[0042] As shown in FIG. 1, a gang switch 32 in its position illustratedconnects the output of sound generator 10 to the patient's headphones12, which preferably is a high quality headset commercially availablee.g. from Bose, Inc. of Massachusetts, USA under the trademarkQuietComfort. If the sound generator 10 does not have a phase shiftfeature, a separate phase shift network 30 of any known type may beutilized. Switch 32, as illustrated, applies the shifted output of soundgenerator 10 via phase shift network 30 to headphones 12. Then thesuccessively phase shifted increments of sinewave tone from generator10, as herein-above explained, successively shifts the generated sinewave relative to f, as illustrated in FIG. 2, to accomplish thereciprocal 180 degree phase canceling relationship through the stepsillustrated as f₁ f₂ . . . f_(n).

[0043] Referring again to FIG. 1, a further direct or essentially onestep phase-shift reciprocal cancellation embodiment of Applicant'simproved apparatus and method for treating monofrequency tinnituspatients will be described. The patient sound-typing is accomplished, ashereinabove described, by adjusting the frequency and amplitude knobs18-2 and 20-2 of sound generator 16 until the desired match with thepatient's tinnitus tone and amplitude are achieved. Then, as in thepreviously described embodiments disclosed above, the like frequency andamplitude knobs 18 and 20 of sound generator 10 are set to like settingsof generator 16 and the phase shift knob 22 of sound generator 10 isadjusted in a direct or essentially one step motion to bring the outputwave form of sound generator 10, which is also applied to oscilloscope14, into a phase shift, reciprocal, canceling relationship of 180degrees relative to the output wave form of sound generator 16 which isalso displayed on oscilloscope 14. As hereinabove described withreference to FIG. 2, this phase canceling reciprocal wave formrelationship with regard to the respective outputs of sound generators10 and 16 is depicted as the sum of f₁+f_(n) which verifies theidentical match between the generated treatment tone of sound generator10 and the patient selected tinnitus tone. As hereinabove explained withrelation to the previous described embodiments, the phase shifted outputof signal generator 16 is directly applied to the tinnitus patient viaheadphones 12 preferably for a time period in the order of ten minutesfor each patient treatment. In this alternative embodiment, switch 32remains in the position indicated in FIG. 1 as the phase shift networkis not utilized. However phase shift network 30 and switch 32 may beutilized to effect a 180 degree shift of generator 10 output in lieu ofthe phase shift adjustment described above utilizing knob 22 of soundgenerator 10.

[0044] Referring now to FIG. 3, there is illustrated in a logic flowdiagram one of Applicant's preferred sequence of steps to accomplishApplicant's phase shift treatment for mono-frequency tinnitus patients.In Step 1 a patient's eligibility for the phase shift treatment isdetermined in a medical-audiologic tinnitus patient protocol (MATPP) orsimilar medical protocol. The medical-audiologic examination determinesif Applicant's phase shift treatment is appropriate for the patient andwhat if any cause can be ascribed for a particular patients condition.As is known to those skilled in the Tinnitus Medical and AudiologicArts, tinnitus classification generally employs four major factors: (1)localization, (2) intensity, (3) sound types or composition, i.e. puretone or complex tones, and (4) temporal variability of the tone(s). Atpresent only pure tone, non-drug induced monofrequency tinnitus appearsappropriate for this first evolution of Applicant's phase shift tinnitustreatment program. For a more complete understanding of MATPP see“Medical-Audiologic Tinnitus Patient Protocol” in Shulman, Chapter 15.

[0045] Steps 2, 3 and 4 provide for the subjective “sound-typing” by thepatient which generally involves matching the output of an externalsound wave generator to the tone (frequency) and amplitude (loudness) tohis/her monofrequency tinnitus tone. In accordance with Applicant'spreferred embodiment, this patient subjective “sound-typing” isaccomplished in a soundproof environment illustrated as movable member36 in FIG. 1, in a sequence of at least five sequential trials, each ona blind basis, where the patient is not able to determine visually theoutput of the sound generator by viewing any of the dials or displays onthe sound generator 10. If there are any major differences in themultiple “sound-typing” steps further tests are conducted to ensureoctave confusion or other errors by the patient are not involved.

[0046] In Step 5, utilizing the subjective patient data from Steps 2, 3and 4, a pure tone sinusoidal wave form from the external soundgenerator is generated which is substantially identical to the patient'stinnitus tone in both amplitude and frequency.

[0047] In Steps 6 and 7, the generated sinusoidal wave form issequentially phase shifted through a series of steps a predeterminedamount (delta 1, delta 2 . . . delta n as shown in FIG. 2.). Where thepredetermined phase shift increments add up to at least 180 degree phaseshift relative to an arbitrary reference and where the generated toneand the patient's tinnitus tone are the same frequency and amplitude,the generated tone is brought into a reciprocal, cancellationrelationship with the patient's tinnitus tone. This sequential phaseshift iteration is useful and indeed necessary in practicing thisembodiment of Applicant's sequented step phase cancellation treatmentbecause at present there are no instrumentation processes to directlymeasure the phase relationship between a patient's monofrequencytinnitus tone and the externally generated sinusoidal tone. However theincremental 180 degree shift brings the generated sound wave at somepoint into a reciprocal relationship (i.e. canceling) relative to thepatient's tinnitus tone.

[0048] In the alternative direct or essentially one step embodimentdescribed above, there is no need for the sequential or incrementalphase shift steps described in Steps 6 and 7 of FIG. 3 as the desiredphase shift of 180 degrees is implemented directly or in essentially onemotion by using the phase shift feature of sound generator 10. Aspreviously described, the respective output wave forms of soundgenerators 10 and 16 may be algebraically added or summed to producewave form or tone cancellation as shown in FIG. 2. Such total tonecancellation feature of this embodiment is significant for Applicant'simproved monofrequency tinnitus patient treatment because itconveniently verifies the identical match between the treatment tone andamplitude with the subjective patient determined tinnitus tone andamplitude or loudness which has been found to be useful. Thus in lieu ofthe sequential, phase shift steps described in Steps 6 and 7 of FIG. 3,in this alternative embodiment the output wave form of sound generator10 is directly shifted through 180 degrees to bring it into phasecanceling, reciprocal relationship with the output of sound generator 16and the phase shifted output wave form of sound generator 10 is thenapplied to the tinnitus patient directly via headphones 12 for apredetermined time period preferably in the order of ten minutes pertreatment.

[0049] The phase shift of the generated wave form is preferablyaccomplished utilizing a phase shift feature of the Agilent soundgenerator 10, as hereinabove described. Alternatively the sequential ordirect phase shift of the generated wave form may be accomplished in aphase shift network 32 which as described above the output of which maybe selectively coupled to the patient's headset 12 via switch 32. Ineither instance, these phase shift increments or direct phase shift stepmay be manually selected by the attending audiologist/physician or itmay be automated using an appropriate timing circuit, not shown, inconjunction with the phase shift network 32. In either event withinApplicant's preferred embodiment, each increment or direct step of thephase shifted wave form is preferably coupled to the patient's headset12 for a period in the order of 10 minutes and in utilizing theincremental steps each incremental phase shift is in the order of 20degrees whereby a patient treatment for the full 180 degree shift wouldbe, in the order of 90 minutes. For the direct step phase shiftembodiment embodiment, the shifted waveform is likewise coupled to thepatient's auditory system for a predetermined period of time, preferablyten minutes.

[0050] Step 8 is intended to enable the attending physician and thepatient to subjectively evaluate the effectiveness of a phase shifttreatment in minimizing or alleviating entirely the deleterious patienttinnitus condition. A patient diary is preferably kept to record data atpredetermined intervals after a phase shift treatment is completed andthereafter at several daily intervals before the next treatment. Thediary should record patients subjective data regarding the loudness ofhis/her tinnitus tone (e.g. on a 1-10 scale where 1=0 or negligibleloudness, 5=intermediate loudness and 10=very loud. Preferably thepatient diary additionally includes data regarding: 1) where does yourtinnitus tone appear to be located? ?) if more than one location, whichlocation is worse? 3) has your tinnitus tone changed appreciably or doesit appear to be more than one tone? and 4) does the location of yourtinnitus tone tend to fluctuate in tone or loudness? Data from thepatient's diary is useful in planning subsequent patient treatmentroutines and schedules.

[0051] Referring now to Table 1 below, the subjective, patientdetermined data for a monofrequency tinnitus phase shift patienttreatment study for twenty-three patients is reported. Table 1 reportson a clinical single blind study which was conducted in New York underthe direction and control of Applicant.

[0052] A brief description of the study methodology hopefully will setthe stage to more fully understand the data reported in Table 1. Patientvolunteers with monofrequency tinnitus only were selected throughresponses to newspaper advertisements. Each patient completed a consentform agreeing to come to the designated office once a week for eightweeks to participate in a single blind study in which 50% of the studygroup would initially receive Applicant's sound cancellation tinnitustreatments and the other 50% would initially receive a placebo or shamtreatment. After four weeks there would be a cross-over, i.e. the shamtreatment group would begin receiving Applicant's sound cancellationtreatments and the previously treated group would receive during thesame period only sham treatments.

[0053] Each patient was asked to keep a daily tinnitus diary or log ofhis/her subjective estimate of tinnitus intensity on a scale of 1-10,with 10 being the patient's own usual level of tinnitus tone and 1 beingminimal or negligible tinnitus tone intensity. Each patient was asked tomake recordings daily at 0800 and 1600 hours respectively. At theinitial screening session, a relevant patient medical history wasobtained and the program methodologies were fully explained. At eachweekly treatment session, each patient was asked to deliver theirrespective diaries to a program staff assistant, but they were not shownor discussed with the physician or audiologist administering the test orto Applicant.

[0054] Each patient was “sound-typed” as hereinabove explained inconnection with FIG. 3 with each patient manipulating an adjustablefrequency (tone) dial on an Agilent 33250a generator or its commercialequivalent. Each patient then similarly determined the amplitude orloudness of his/her tinnitus tone. These steps were repeated a number oftimes to ensure the accuracy of a patient's sound typing data and testswere repeated if a particular patient's results varied from try to tryby more than 10% until exact determinations were assured. Care was takento avoid octave confusion where sound typing may result in a frequencywhich is a multiple or submultiple of the actual tinnitus tone.

[0055] Applicant's frequency cancellation tinnitus treatment began withthe patient's sound type data being set up on a first sound generatorand like tone and amplitude data then set up on a second sound generator(see FIG. 1, sound generators 16 and 10 respectively) and the outputwave forms from sound generators 16 and 10 coupled as inputs to anoscilloscope 14. With identical wave forms from sound generators 16 and10 displayed on the oscilloscope 14, the phase shift knob 20 of soundgenerator 10 is utilized to shift the phase of output wave form of soundgenerator 10 directly or essentially in a single continuous movementinto a reciprocal, 180 degree relationship with the output of soundgenerator 16. By summing the output wave forms from sound generator 16and the phase shifted tone output from sound generator 10, the phaseshifted reciprocal relationship of the two wave forms (See FIG. 2) canbe observed and then the phase shifted wave form from sound generator 10is also sent to the patient's auditory system via headphones 12 for atreatment period of 10 minutes. For the placebo or control grouptreatments, the sound wave was not phase shifted but set at a steadylevel of 100 hertz at 50 milivolts for a treatment period of 10 minutes.At the beginning and end of each treatment session, the patient'stinnitus tone amplitude was again subjectively determined, ashereinabove described.

[0056] To simplify summary study data entry in Table 1, the followingconventions were utilized to characterize each patient's subjectivetinnitus status which were then combined following completion of theeight weekly treatments into the following categories:1=Excellent—complete or near complete relief with loudness reduction of90% or more; 2=Very Good—strong partial relief response in the order of75% loudness reduction; 3=Good—partial relief response in the order of50% loudness reduction; 4=Fair—partial relief in the order of 25%loudness reduction; and 5=Poor—minimal or no relief from originaltinnitus condition.

[0057] Referring now to Table 1, as is shown of the twenty-three treatedpatients, seven patients experienced complete or nearly complete relief(1 s); four patients experienced strong partial relief (2s) withloudness reduced in the order of 75%; eight patients experienced goodpartial relief (3s) with loudness reduced in the order of 50%; onepatient experienced partial relief with loudness reduced in the order of25% (4); and three patients experienced no or negligible relief fromtheir original tinnitus condition (5s). None of the patients experiencedany increase or aggravation of his/her original tinnitus condition. Asshown, the study encompassed a wide range of tinnitus tone levels and awide range of individuals who had suffered from tinnitus for many years.

[0058] It is important in evaluating the Table 1 data to recognize thatthe response of all of the placebo or control patients was a #5—minimalor no relief response from their respective original monofrequencytinnitus condition (5s). When compared to the nineteen responses in thetreated patient group of twenty-three patients, it is statistically verysignificant and yields a p-value of p=0.001.

[0059] As is well known in the medical arts, tinnitus has many differentforms and different causes. A survey of medical tinnitus treatmentliterature clearly demonstrates how difficult a problem treatingtinnitus patients truly has been over the years and that there iscurrently no known cure for tinnitus. Vernon has recently reported in1998 that early optimistic reports of tinnitus cures in the order of 80%are in drastic contrast to more humble results from various other recentclinical experiences. However, for those who suffer substantial medicaldisability from tinnitus, any, even temporary relief can be significanteven if their tinnitus is not completely or permanently cured. The dataof Table 1 demonstrates that a total of nineteen treated patients (82%)achieved at least a 50% reduction in their tinnitus loudness and morethan 30% reported complete or nearly complete (more than 90% loudnessreduction) relief.

[0060] While the tinnitus patient treatment study reported in Table 1utilized primarily the embodiment of Applicant's improved treatmentapparatus and methods which utilizes direct or one-step phase shiftcancellation adjustments, the other sequential, incremental-step phaseshift adjustments embodiments are equally applicable and additionalstudies are and will be directed to those other embodiments ofApplicant's inventions as distinctly claimed in the appended claims.TABLE 1 Tinnitus Phase-Shift Cancellation Treatment Clinical SingleBlind Study Subject Tone Classification Subjective Status Patient # AgeYears (mhz/milivolts) After Treatment 1 50 17  11.7/1000 1 2 67 590.20/100  1 3 72 15 3.60/272  1 4 66 2.5 6.50/110  1 5 64 4 2.40/117  16 55 4 4.40/50   1 7 48 10 6.31/102  1 8 60 6 1.60/107  2 9 66 23.40/70   2 10 30 2 2.38/50   2 11 49 15 3.02/96   2 12 73 35 0.833/62  3 13 66 7 0.100/126   3 14 65 15 0.10/84   3 15 52 27 5.50/50   3 16 735 0.100/73   3 17 57 21 1.93/50   3 18 84 15 3.70/84   3 19 67 5.50.100/86   3 20 53 10 6.00/10   4 21 63 15 0.64/90   5 22 54 6 2.20/30  5 23 56 2.5 8.10/35   5

[0061] While Applicant's improved apparatus and methods for treatingmonofrequency tinnitus patients utilizing phase-shift cancellationprinciples have been described in connection with several specificembodiments thereof, it is to be understood that these embodiments areby way of illustration and not of limitation, and therefore the scope ofthe appended claims of Applicant's novel inventions are to be construedand interpreted as broadly as the relevant prior art will permit.

What is claimed is:
 1. Apparatus for treating monofrequency tinnituspatients comprising: a sound generator having adjustable frequency andamplitude controls for selecting an output tone having a predeterminedfrequency and amplitude, a pair of headphones to be worn by the patientfor coupling the output of said sound generator to said patient toenable the patient to subjectively match the output tone of saidgenerator to the patient's tinnitus tone, a phase shift network forselectively shifting the phase of said output wave form of said soundgenerator through a plurality of discrete incremental phase shift steps,and means to selectively connect the phase shifted output wave form tothe tinnitus patient via said headphones to effect phase shiftcancellation between the output of said sound generator and thepatient's tinnitus tone in order to diminish or eliminate the tinnitustone perceived by said patient.
 2. The apparatus of claim 1 wherein saidsound generator and said phase shift network are combined withindividually selectable outputs.
 3. The treatment apparatus of claim 1wherein said phase shift network is integrated as an operator selectablefunction of said sound generator and further including a phase shiftcontrol to select phase shift increments in the order of 10 degrees to180 degrees.
 4. Apparatus for treating monofrequency, pure tone tinnituspatients comprising: sound generator means for generating pure tone waveforms having selectively variable frequencies and amplitudes, acousticheadset means for coupling the output of said sound generator means tobe heard by said patient to enable the patient to subjectively match thefrequency and amplitude of the output of said sound generator means tosaid patient's tinnitus tone, phase shift means for selectively shiftingthe phase of said generated tone relative to a selected reference pointto bring the generated tone into a reciprocal, canceling relationshipwith the patient's tinnitus tone, and means for selectively couplingsaid phase shifted generated tone to said acoustic means for applicationto the tinnitus patient.
 5. The apparatus of claim 4 wherein said meansfor coupling each increment of the phase shifted tone to said patientfor a predetermined time period.
 6. The apparatus of claim 5 whereinsaid means for coupling said phase shifted tone to said patientcomprises a time period in the order of ten minutes.
 7. A method formedically treating a monofrequency tinnitus patient comprising the stepsof: having the tinnitus patient sound-type his/her tinnitus tone bysubjectively comparing the tone and the loudness of an independentlygenerated tone with the patient's tinnitus tone, effecting a phase shiftof the independently generated tone relative to a pre-selected referencethrough 180 degree phase shift, and coupling the phase shifted tone tobe heard by said patient as the generated tone is brought into areciprocal phase canceling relationship with said patient's tinnitustone.
 8. The method of claim 7 wherein the step of subjective patientsound-typing is repeated a plurality of times both as to the frequencyand amplitude of said generated tone.
 9. The method of claim 8 whereinthe step of subjective patient sound-typing is repeated on a blindbasis, whereby the patient is unaware of any readout which wouldcharacterize the frequency or amplitude of the generated tones.
 10. Themethod of claim 8 wherein the step of tone sound-typing comprises afirst step of matching the tone frequency and a second step comprisesmatching the tone loudness.
 11. A method of medically treating amonofrequency tinnitus patient comprising the steps of: having thetinnitus patient adjust the output tone of an external sound generatorto subjectively sound-type the patient's tinnitus tone in terms offrequency and loudness, applying the external sound generated tone tosaid patient through a headset, phase shifting the generated tonerelative to a preselected reference point through a 180 degrees wherebysaid generated tone is shifted into a reciprocal, phase cancelingrelationship with the patient's tinnitus tone, and applying said phaseshifted generated tone to the patient for a predetermined time period.12. The method of claim 11 wherein the step of applying said phaseshifted generated tone comprises a period in the order of at least tenminutes.
 13. The method of claim 11 wherein the step of subjectivelysound-typing includes a first step of matching the tone of saidpatient's tinnitus tone with the externally generated tone andthereafter subsequently includes the step of matching the loudness ofsaid generated tone to the loudness of said patient's tinnitus tone. 14.The treatment apparatus of claim 1 or claim 4 additionally includingloudness control means to enable the tinnitus patient to subjectivelymatch the loudness output of said sound generator to the loudness of thepatients tinnitus tone.
 15. Improved apparatus for medically treatingmonofrequency tinnitus patients comprising: a first sound generatorhaving adjustable frequency and amplitude controls for generating anoutput tone having a first predetermined frequency and amplitude, asecond sound generator having adjustable frequency and amplitudecontrols for generating a second output tone having a secondpredetermined frequency and amplitude, a dual trace oscilloscope fordisplaying the output wave forms of said first and said second soundgenerators and for selectively algebraically summing the output waveforms of said first and said second sound generators, a phase shiftnetwork for selectively shifting the phase of the output wave form ofone of said sound generators relative to a predetermined point toachieve a 180 degree phase shift relative to the output wave form of theother of said sound generators, and acoustic headphones for coupling theoutput of said phase shift network to the auditory system of saidpatient to be treated.
 16. The improved treatment apparatus of claim 15additionally including control means for sequencing an output of saidphase shift network through a plurality of discrete incremental phaseshift steps to achieve said 180 degree phase shift.
 17. The improvedtreatment apparatus of claim 15 additionally including control means fordirectly shifting the output of said phase shift network into a 180degree reciprocal, phase canceling relationship with the output tone ofsaid other sound generator.
 18. The improved treatment apparatus ofclaim 17 wherein said control means comprises means for accomplishingsaid 180 degree phase shift in a single step wise manner.
 19. Animproved process for medically treating a monofrequency tinnitus patientcomprising the steps of: having said tinnitus patient sound-type his/hertinnitus tone by subjectively comparing an output wave form of a soundgenerator with the patient's tinnitus tone, externally generating asecond tone equal in frequency and amplitude to said patient's tinnitustone, displaying on a dual trace oscilloscope wave forms correspondingto said patient's tinnitus tone and said second generated tone toachieve an algebraic summing and cancellation of said two displayed waveforms when they are in a reciprocal out of phase relationship, shiftingthe phase relationship of an output wave form of said externallygenerated second tone relative to a predetermined point by 180 degreesto bring said externally generated tone into a phase shifted reciprocal,canceling relationship with said displayed patient's tinnitus tone, andapplying said phase shifted generated tone to said patient's auditorysystem to effect a phase shift, reciprocal canceling relationshipbetween said phase shifted generated tone and said patient's tinnitustone to diminish or eliminate the tinnitus tone perception by saidpatient.
 20. The improved process of claim 19 wherein the step ofshifting includes the additional step of sequencing said shiftingthrough a predetermined number of incremental steps totaling 180degrees.